First of all it's not right that he has been a member of this site as long as you were together. Meaning he pretended to be someone else to you.
If he'd have been honest with you from the beginning. Then you could have made your choice if you wanted to get into a relationship with a man who enjoys watching porn or not.
He never left you that choice and that's very wrong!!!
From the beginning he wasn't honest with you about something important! Probably out of fear of not being able to get and to keep you as his partner. That's a lame excuse.
Because now you just have found out that you're with a man who lied to you for as long you were together.
Very normal that you are starting to think about what else has he been lying to me?
That you want to get an inside into his bank cards and everything. Has he seen other behind my back? Is this the reason why we barely have any sex?
I've no experience in such a situation, but if possible I think I'd make it very clear to him that I don't tolerate this.
I'd kick him out immediately!
I'd tell him what I've found out. I'd tell him that I'm furious that he hasn't been honest with me for as long as we're together.
If he wants to come back to me that's ok. But on my terms!!!
I want the truth at all times. I want to be able to have a look whenever I want in your bank statements.
I also want to feel that you truly love me.
Show me your love, being open and honest in everything and you're able to get back to me. Or else goodbye!
It must be so hard for you. But I'm afraid that if you don't stand up for yourself at this moment. He might think he got away with it or that he can continue to play with you. You got to show him what you're made of!!!
It must be hard to learn the real truth about someone. Although it will hurt so much. I hope you also can be happy about you finding this out. Otherwise he would have continued to watch porn behind your back and who knows what else.
Now you know it you can do something about it.